Synthetic fibers have achieved widespread consumer acceptance. Typical examples of such synthetics include the polyester fibers such as Dacron, Kodel, Vycron, Terylene, Fortrel, Encron and Trevira; the acrylic fibers such as Acrilan, Orlon and Creslan; cellulose acetate such as Arnel and Tricel; polyamide such as nylon; polyolefins such as polypropylene. In addition there can be employed the modifications of the above hydrophobic textiles such as acid modified polyester, deep dyeable polyester, cationic dyeable polyamide, modacrylic and such newer materials as Qiana.
These hydrophobic materials usually cannot be dyed by ordinary dyeing procedures as have been previously used for dyeing such fibers as cotton, wool, silk, regenerated cellulose and the like. When such conventional dyeing procedures are used with hydrophobic textiles, the dye usually does not penetrate the textile and either no dyeing is obtained or a very poor quality dyeing results. If dyeing does not result, the color is usually not fast and tends to wash out of the textile. Due to these dyeing difficulties, the dyeing of hydrophobic synthetic fibers is generally effected by other methods such as for example by the use of a dye carrier in the presence of a swelling agent. These components tend to open the pores of the hydrophobic fibrous material and permit the dye to enter and remain there in a colorfast manner.
As a result of the problems incurred in dyeing and printing synthetic fibers a tremendous amount of work was commenced to discover appropriate compounds and compositions that have the property of increasing the rate of dyeing of synthetic hydrophobic fibers when added to the dyebath. These compounds and compositions are generally called carriers and in the past ten or so years extensive research has been carried out relative to these carriers.
In addition to having a swelling action, any useful carrier must have a high efficiency, should have no effect or enhance the fastness properties of the dyed fibers and should not degrade or discolor the fiber in question. The carrier should be readily removed from the fiber after dyeing, and it should be stable under the conditions of the dyebath. In addition to these properties the carrier should be compatible with dyes employed, should leave no residual odor in the finished textile and should not be toxic.